I've used the contour HD during my training. There is a new model out which records full 1080 HD. My camera is only 720 HD but still has excellent picture quality. I used velcro to attach it to my David Clarks, using the little lanyard supplied just in case the velcro let go (It never has). I like the fact that the camera has a built in laser for making sure all is level. Plus the quality is good enough to be able to read the instruments as well as taking in the scenery.
On the down side there is no input for an external mic, so you have to make do with the built in mic which is a bit rubbish.
I looked at the GO PRO but you need to have it facing forward and I thought I'd look even more of a numpty with a box on top of my head.
Hope this helps.
Monkey